1. Field of the Invention
The present invention relates to orthodontic devices and, more particularly, to an orthodontic device capable of individually adjusting the row of teeth on the upper or lower jaw to the normal tooth positions by means of a resilient restoring force resulting from a height difference between the two ends of a U-shaped metal wire.
2. Description of the Prior Art
Orthodontics is a branch of dentistry that provides a variety of treatments for people who suffer from malocclusion or who are not satisfied with their looks because of tooth irregularity, disproportionate jaw relationships, or both. Malocclusion may result from congenital maxillary/mandibular hyperplasia or hypoplasia, tooth abnormalities, or a size mismatch between the teeth and the dental arches. The various conditions of malocclusion include crowding of teeth, crossbite, forward or backward projection of teeth, excessive spacing between teeth, tooth impaction, misalignment of teeth due to congenitally missing teeth or supernumerary teeth, and so on. Bad oral habits may also lead to such malocclusion problems as openbite, crossbite, and a narrow upper dental arch.
Therefore, orthodontic devices are designed to improve the abnormal development of facial bones, rearrange misaligned teeth, and thereby achieve the following therapeutic purposes:
1. To restore mastication function and thereby improve digestion and the absorption of nutrients;
2. To facilitate the maintenance of oral hygiene and thereby prevent tooth decay and periodontal diseases;
3. To enhance facial esthetics for higher self-confidence and thereby promote normal character development;
4. To enable correct pronunciation and thereby increase learning efficiency; and
5. To enable proper occlusion and lip closure, thereby preventing dryness of the oral mucosa and enhancing the resistance of the oral cavity against infection.
Orthodontic treatments are generally classified as follows, according to the orthodontic appliances used:
1. Fixed orthodontic brackets: According to the patient's liking, orthodontic brackets made of metal, transparent ceramics, or compounds are cemented to the outer or inner sides of the patient's teeth by an adhesive and serve as a medium for delivering force to the teeth.
2. Removable orthodontic devices: Orthodontic plates are placed in the patient's mouth and can be easily removed for easy maintenance of oral hygiene.
3. Jaw bone correction appliances:
(1) An extraoral traction appliance is worn on the patient's head to generate a traction force that influences bone growth.
(2) An intraoral functional orthodontic appliance uses the patient's muscles and biting action to generate an orthodontic force that influences the development of the lower face.
A conventional fixed orthodontic device typically includes a straight orthodontic wire fixed in position by rubber bands to a plurality of orthodontic brackets cemented to the tooth surfaces. Each end of the orthodontic wire is attached via a spring to an orthodontic screw implanted in the alveolar bone, so as for the springs to exert a pulling force and thereby pull the skew or misaligned teeth to the normal positions, with a view to correcting jaw position. However, such a conventional orthodontic device is applicable only to horizontal adjustment (e.g., the correction of crowded teeth, forward- or backward-projecting teeth, excessive spacing between teeth, congenitally missing teeth, etc.) but is not suitable for adjusting an inclined row of teeth caused by a vertically tilting upper or lower jaw.
Besides, installation of the conventional fixed orthodontic devices involves local anesthesia and implantation of orthodontic screws into the alveolar bone where the tooth roots are not located. Moreover, the springs which are used to tighten the orthodontic wire do not have direct corrective effect on the jaw bone. Hence, not only are the installation and removal of the orthodontic devices complicated, but also the patients will have to endure pain and discomfort during the installation and removal processes.